Variable spray device for dishwasher



J. W. JACOBS VARIABLE SPRAY DEVICE FOR DISHWASHER April 18, 1961 3 Sheets-Sheet 1 Filed March 30. 1959 James (4/. Jacobs ms ATTORNEY April 18, 1961 J. w. JACOBS 2,980,120

VARIABLE SPRAY DEVICE FOR DISHWASHER H15 ATTORNEY April 18, 1961 J. w. JACOBS VARIABLE SPRAY DEVICE FOR DISHWASHER 5 Sheets-Sheet 3 Filed March 30, 1959 IINVENTOR. James M. Jacobs 6 ms ATTOR/Viy w o 0 a o o 6 w w w w w 70 80 .90 I00 /10 A?!) I39 /90 1:70 [60 BIMETAL TEMPERATURE Unit States aten 1Q," c

2,980,120 VARIABLE SPRAY DEVICE FOR DISHWASHER Filed Mar. 30, 1959, Ser. No. 802,947

14 Claims. (CL 134-.57)

This invention relates to a domestic appliance and more particularly to an improved dishwasher.

In the dishwashing art it has been conventional practice to utilize a dishwashing chamber in which is disposed a means for distributing water throughout the dishwashing chamber. In some'of the prior art dishwashers the water distributing means have taken the form of an impeller located in the bottom or sump of the dishwashing chamber for impelling water or washing fluid from the sump to the soiled dishes disposed in the chamber thereabove. Another method of distributing water in a dishwashing appliance is shown in the patents to Abresch et a1. 2,734,520 issued February 14, 1956, and 2,808,063 issued October 1, 1957. In the Abresch machine water collecting in a sump at the bottom of the dishwashing chamber is pumped to a rotatable spray tube in an upper portion of the washing chamber from which point the water is ejected forcefuLy over the surfaces of the articles to be cleaned. In both the bottom impeller type dishwasher and in the rotating spray tube machine the spray pattern is preset by the initial design of the impeller or spray tube. Consequently once a soiled dish or utensil is placed in a generally fixed position within the washing chamber, it will be exposed to the same spray pattern throughout the water distribution cycles of the machine.

Accordingly it is an object of this invention to provide a washing appliance having means for circulating a washing fluid with means for altering the manner in which the washing fluid is circulated.

Another object of this invention is to provide a washing appliance having a washing fluid distribution system with means for changing the distribution in response to a changing condition within the washing appliance.

Another object of this invention is to provide a washing appliance having a washing fluid distribution system with means for changing the distribution in response to a changing thermal condition.

A further object of this invention is to provide a dishwasher of the washing fluid circulation type with means for varying the washing fluid circulation in response to a thermal change within the dishwasher.

A more specific object of this invention is to include in a dishwasher a rotatable spray tube, means for pumping washing fluid to said spray tube, and swirl inducing means in the path of said washing fluid, said swirl inducing means being positioned in accordance with the temperature of said washing fluid.

It is also an object of this invention to provide a fluid distribution system including a spray tube, a pump and conduit means connecting said pump and spray tube with swirl inducing means in said conduit to cause rotation of said spray tube, said swirl inducing means being periodically altered in timed sequence. 7

Still another object of this invention is to provide in a fluid distribution system a spray tube, conduit means for carrying washing fluid to said spray tube, and a movable vane in said conduit for imparting a rotary motion to the washing fluid;

I Patented Apr. 18, 1951 A more specificfeature of this invention is incorporated in the last cited object wherein the vane is a thermally responsive device. p

Also an object of this invention is the provision of a spray tube which may be rotated at different speeds in different directions.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred forms of the present invention are clearly shown.

In the drawings:

Figure 1 is a schematic diagram of a dishwasher suitable for use with this invention;

Figure 2 is a fragmentary sectional view of a spray tube and the novel means for imparting swirl to fluid pumped to the spray tube;

Figure 3 is a side elevational view of a solenoid operated, adjustable swirl imparting vane chamber;

Figure 4 is a sectional view of the solenoid operated swirl inducing vanes taken along line 44 of Figure 2;

Figure 5 is a schematic wiring diagram for operating the dishwasher in accordance with one concept of this invention;

Figure 6 is a sectional view of a second embodiment of this invention;

Figure 7 is a sectional view of the second embodiment of this invention taken along line 7-7 of Figure 6;

Figure 8 is a graphic representation of spray tube speed versus bimetal tempertaure during a washing cycle;

Figure 9 is a sectional view of a third embodiment of this invention; and

Figure 10 is a sectional view taken along line 1010 of Figure 9 of this third embodiment.

In accordance with this invention and with reference to Figure 1 a dishwasher 10 is formed with a dishwashing chamber 12 having a front opening 14 closed by a pivotally mounted door 16. The dishwashing chamber 12 is formed with a sump 18 at the bottom thereof to which is connected a pump 20 driven by a motor 22. In the upper part of the dishwashing chamber is a spray tube 24 which is rotatably supported at its open rear end 26 on a spray header 28 and at its closed front end 30 on pin or shaft 32. The shaft 32 is carried by a bracket 34 affixed in any suitable manner to the rear wall 52 of the dishwashing chamber 12 or to the spray header as indicated in Figure 6. Connecting the spray tube 24 and the pump 20 is a conduit 36 in which a two-position valve 38 is positioned to selectively direct water upwardly through conduit 36 to the spray tube 24 or downwardly through a conduit 40 to drain. Perforated dish supporting racks 42 are removably positioned within the dishwashing chamber 12 in a manner to expose any soiled dishes or utensils to the washing fluid ejected from the slots or ports 25 of the spray tube 24. In brief the spray tube 24 is designed to rotate in response to the spiral movement of water or washing fluid proceeding longitudinally from the open end 26 of the spray tube 24 to the closed end 30. Swirl or rotary motion is imparted to the washing ,fluid traveling along the spray tube 24 in accordance with the concepts of this invention to be described more fully hereinafter.

Disposed in the sump 18 is a heater 44 which is selectively energized during a dishwashing cycle. Water is admitted to the sump 18 by means of an inlet water valve 46 and the general sequential operation of the dishwasher 10 is under the control of a timer 48 which selectively actuates the various components of the dishwasher 10 in accordance with conventional dishwashing practice. For the purposes of this invention the foregoing explanation is believed to suffice. However, for further details on the dishwasher of this general type reference may be had to the aforementioned patents to Abresch. et' aL,

tional means 72.

2,734,520 and 2,808,063. Note, however, in both of these prior art patents the water directed to the rotatable spray tube follows a fixed pattern dictated by the design of the swirl inducing spray head and consequently the spray tube will rotate in a predetermined manner throughout a dishwashing cycle.

It has been found in prior art machines that soiled utensils and dishware are exposed solely to one spray pattern. Therefore, if a particularly soiled area is not impinged upon directly by the action of the spray, this area will not be properly cleaned. It is here proposed'to vary the spray pattern issuing from the slots 25 of the spray tube 24 by varying the speed and the direction with which the spray tube is rotated. Since the speed of rotation of spray tube 24 is dependent on the amount of swirl or rotary motion imparted to the washing fluid entering the open inlet end 26 of the spray tube, such rotary speed can be varied in accordance with the amount of rotary or swirling motion imparted to the water being pumped through the spray header 28. Similarly, the direction of the swirl or rotary motion of the water may be changed in order to reverse the direction of spray tube rotation.

With reference to Figure 2 one method is shown for varying the amount and direction of swirl or rotary motion imparted to the pumped fluid. The spray header 28 is shown affixed in the top portion 50 of supply conduit 36 in a manner to receive the washing fluid pumped from the sump 18. The conduit 36 is closed at its upper end 50 and has an opening 51 to which a flange 53 of the spray header 28 is fastened as by a bolt 55. The rear or open end 26 of the spray tube carries an annular bearing ring 54 to provide a bearing surface for the spray tube on the cylindrical outlet 56 of the spray header 28. Thus all fluid being pumped through conduit 36 enters the spray tube 24 through its open end 26 and swirlingly traverses longitudinally of the spray tube (see flow arrows 27) toward its outer closed end 30. This fluid motion sets up rotation of the spray tube 24 relative to spray header outlet 56, the tube 24 being supported at its closed end 30 by the pin 32 in a bearing 58 of graphite material or the like. As the water traverses the spray tube 24 certain portions thereof will be ejected forcefully through the slots 25 and these jets of washing fluid will impinge on the dishes placed within the support baskets 42.

The direction which these jets of water take as they leave the spray tube slots 25 is dependent on the speed with which the spray tube 24 is rotating at the time. To vary the speed of spray tube rotation the spray header 28 includes a boss 60 integrally molded to the rear wall 62 of the spray header 28. A shaft 64 is journalled in the boss 60 and protrudes through and is journalled in an opening in the side wall 66 of the spray header 28. A similar pin 68 is journalled in the central boss 60 and protrudes through and is journalled in an opening in a side wall 70 of the spray header 28. Affixed to pin 64 and pivotal therewith is a swirl inducing vane member or flow direc- A second vane memberor flow directional means 74 is aifixed to pin 68 and pivotal therewith. Thus it should be seen that the swirl inducing vanes 72 and 7 4 are positioned respectively in accordance with the rotational movement of the shafts 64 and 68 which extend outside of the spray header 28. Affixed to the outer'end =nected to link 76 at 94, and a depending arm or car 96 .pivotally connected 'to'link 78 at -98. Thus the vertical of pin 64 is a vane actuator link 76 and to the pin 68 a I reciprocation of the armature 84 will cause the actuator bracket 88 to rise and fall, thereby positioning or altering the position of swirl inducingvanes 72 and 74. In other words vane 72 is lifted as vane 74 is lowered and vice versa. More particularly with vane 72 in raised position and vane 74 lowered, a counter-clockwise motion will be imparted to the washing fluid and consequently the spray tube 24 is viewed from the spray tube end 30 looking toward the spray header 28. Conversely with vane 74 in raised position and vane 72 lowered, a clockwise motion or swirl will be imparted to the pumped fluid and the spray tube 24 will respond thereto by rotating clockwise.

In order to make the speed of the spray tube 24 adjustable the solenoid actuating assembly includes a counter-clockwise speed adjuster and a clockwise speed adjuster 102. The adjuster 100 serves as an upper stop for the reciprocating armature 84. Thus by threading the adjusting nut 100 inwardly, the upward movement of armature 84 is limited and the angular positioning of vane 74 to vane 72 is made smaller. When the angle is decreased theamount of swirl imparted to the water is decreased also and the spray tube 24 rotates more slowly. Similarly, the vertical positioning of adjusting knob 102 limits the downward travel of arm 104 on the armature 84 and the clockwise speed of the spray tube 24 may be adjusted accordingly. vIn order to make the solenoid actuating mechanism 80 water-tight a bellows 186 of any conventional design is included about the armature extension 86 to prevent water from entering. It should be noted that the above described arrangement provides for reversing the spray tube during dishwasher operation. Note also that the spray tube rotational speed may be predetermined for any given cycle by means of adjusting knobs 100 and 102.

The operation of the solenoid actuated swirl inducing vanes is believed best understood with reference to the schematic wiring diagram of Figure 5. The circuit could include a door switch 108, a main line on/off switch 110, a pump motor 22, a drain valve 38, a fill valve 46, a heater 44, and a pilot light 112 to indicate machine opera.- tion. Also included in the circuit is a timer motor 114 which acts to sequentially position a pump motor timer switch blade 116, a drain valve timer switch blade 118, a fill valve or heater timer switch blade 129, and a timer switch blade 122 in control of the solenoid 82 for actuating the swirl inducing vanes 72, 74. With the exception of the portion of this circuitry directed to controlling the vanes 72 and 74 the timer control arrangement is believed conventional and directed merely to selectively energizing and deenergizing the various components of the dishwasher in proper sequence. Water from valve 46 will first be admitted to the sump pump 18. Subsequent-1y the pump motor 22 is energized to circulate water to a spray tube 24. After this the drain valve 38 is energized for permitting the wash water to drain from the washing chamber 12. One or more rinse cycles may follow the wash in which clear water is admitted to the dishwashing chamber 12 through the water supply valve 46. Clear rinse water is circulated by the pump 26 and after which the drain solenoid 38 is energized to remove the rinse water from the sump 13. Throughout the dishwashing cycle the timer motor 114 is energized and in accordance therewith the swirl inducing vanes 72 and 74 are moved at selected points in the dishwashing cycle as set forth immediately hereinafter.

Periodically during the wash and rinse cycles timer switch blade 122 is closed to energize the vane operation solenoid 82. This causes the solenoid to overcome the bias of spring 101 and shift the vanes 72, 74 to a different position which will reverse the spiral direction with which the water enters the open end 26 of the spray tube 24. Thus the rotational direction of the spray tube 24 is periodically reversed to provide a more thorough-and 'an improved washing'action. The adjustable means 169 and '102 are provided for setting the angular displace,-

meat of vanes 72, 74 and thus the parted to the water, thereby controlling the spray-tube speed or revolutions per minute. the vanes 72 and'74 and thus therotating direction of spray tube 24 are under the control of the timer 48 and timer motor 114. -In this embodiment it is necessary only to add to a conventional timer additional means for pro-. viding the selective actuation of the vanes 72 and 74. In the second embodiment, described'next following, a conventional timer may be used and no additions need be made thereto; r

Where it is desired to vary the spray pattern within a dishwashingchamber 12 without altering the timer for controlling the appliance, the'actuator assembly 80 may be 1 replaced with thermally responsive means for controlling the vanes. With reference to Figures 6 and 7; a spray tube header 128 is formed with a boss or enlarged portion 130 extending from the rear wall 143 thereof and having a shoulder 132. A pair of spring vanes 134 and136 are positioned in side by side relationship on the shoulder 132 and fastened by anyconventional means 138 to theboss 130. The springvanes 134 and 136 are designed toassume a natural or normal unbiased upper position as shown by vane 134 in Figure 6. To' actuate the vanes a shaft 140 is journalled at 142 in side wall 144 ofthe spray header 128 and at 146 in the side wall 148 of the housing 128. Rigidly. affixed to the shaft 140 are eccentric cams 150 and 152. Thecams 150 and 152 are disposed oppositely on the shaft 140 so that the, rise orhigh point of one cam will be opposite the rise or high point of the other. As shaft 140 is rotated it should be seen that the spring vanes 134 and 136 will be-permitted alternately to assume their natural position (represented by'the position of vane 134 in Figure 6) when the low point of the respective eccentric cam 150 or 152 is against the vane surface and to assume their downward position (represented by the position of vane 136 in Figure 6) when the high point of the respective eccentric cam is thus biasing them. V

-Forrotating the shaft 140 in accordance with a changing condition within a dishwasher the side wall 1'48 ofthe housing includes-aboss 154 on which is supported' a generallycylindricaljcupvlike housing 156. 'Withinthe amount of spiral im-i The movement of I housing 156 a spiral bimetallic element 158 is'positioned 7 having its outer endl60' affixed to the' shaft 140 and its inner end.162'affixed to the .boss 154. I During a dishwashing cycle the temperature within the chamber 12 is changed. The cycle, is initiated with the chamber at ambient temperature. As the spray tube distributes the hot water, the chamber temperature increases, and this temperature is sensed by the bimetal element housing 156 and the spiral strip 158 therein. As the temperature of the bimetallic spiral strip is varied the shaft 140 will be rotated due to the fixed positioning of end 162 of the bimetallic strip. Thus the rotation of shaft 140 is made thermally responsive to dishwashing chamber tempera: tures as is the repositioning of-the swirl inducing vanes 134 and 136.

The operation of the second embodiment of this invention is believedbest understood with reference to the graph of Figure 8, wherein the spray tube speed in'revolutions per minute is plotted against the temperaturev of the bimetal actuator such as bimetallic strip 158. Let us assume for purposes of explanation that a dishwashing cycle has just been initiated. The vanes 134 and 136 are positioned as shown in Figure 6. Water at approximately 180 is admitted to the sump 18 when solenoid 46 is energized. Since the pump motor 22 is energized, the pump 20 acts to circulate water from the sump 18 to the spray tube 24. However since the components ofthe dishwasher 10 are all at ambientor room temperatures. the hotwater is not effective immediately to bring the temperature of the dishwashingrchamber 12 up to the same temperature.

Since the housing 156 extends into the dishwashing chamber 12, the bimetallic spiral elethem 158 senses the temperature of the dishwashing chamber 12 as the temperature increases The spray tube 24 is first rotated with the dishwashing chamber-12 substantially at room ambient, i.e. approximately70. Consequently the spray tube-24 is rotated at its maximum clockwise speed, namely 600 r.p.m. This'is due to the fact that vanes 134 and 136 are at maximum deflection in the relationship of Figure 6 for clockwise spray'tube rotation. As the temperature within the dishwashing chamber increases the bimetallic element 158will' sense this change and will respond thereto by rotating the shaft 140. As the bimetal temperature increases from 70 to for instance, the shaft will be rotatedthrough an angle of 180. In the course of this action the vane 134 which was uppermost will be repositioned to a lowermost position and the reversewill be true as to vane 136. Also during the time that the bimetal temperature increases from 70 to 80 the rotation of the spray tube 24 will have decreased from a speed of approximately 600 r.p.m. in a clockwisedirection to a standstill at approximately 75 bimetal temperature. Then, due to the repositioning of the vanes 134, 136, the spray tube 24 will be accelerated again in a counter-clockwise direction to a speed of approximately 600 r.p.m. in this counterclockwise direction. This procedure is repeated each 10" increase of temperature of the bimetallic vane actuator 158. Assuming the bimetal 158 achieves a temperature as high as at the end of any given water distribution portion of a complete dishwashing cycle thespray tube .24 will have been reversed nine times and accelerated and decelerated in both the clockwise and counter-clock wise direction from 0 r.p.m. to 600 r.p.m. During this action the spray pattern imparted by the variable speed spray tube 24 will be constantly changing. Such changing spray pattern will serve to cover completely any surface of a soiled utensil with an impinging jet of water. This action is effective to completely cleanse in a manner never before possible the items to be washed. Of course it should be obvious that the spray tube speeds and the number of rotational directional reversing actions therefor is merely a matter of bimetal and vane design. Consequently itis within the purview of this invention to vary the speed and rotational direction of a spray tube in any manner consistent with the claims appended hereto.

A third embodiment of this invention is shown in Figures 9 and 10 and is adapted to use a spray'header attached also to the rear wall 52 of a dishwashing chamber 12. The spray header 170 is formed with a boss 172 on the rear wall 173 thereof which includes a shoulder 174 on which are located a pair of bimetallic vanes 176 and 178 fastened as at 180 to the boss 172 of the spray header. The natural configuration of each vane is as seen in Figure 9. This arrangement works substantially like the second embodiment explained immediately hereinabove. In the embodiment of Figures 9 and 10 however the spray tube 24 is reversed just once in accordance with the deflection of the bimetallic vanes 176 and 178. It should be recognized that the vanes 176 and 178 are oppositely mounted and designed so that with rising temperature, vane 176 will move from a lower position (as shown) to an upper position while vane 178 is moving from an upper position (as shown) to a lower position. In this arrangement each time that washing fluid is pumped through conduit 36, the water will flow over and around the bimetallic vanes 176 and 178 causing them to reverse position in accordance with the sensed temperatures of the water. This gradual reversal will cause deceleration of the spray tube 24 from approximately 600 r.p.m. to 0 r.p.m. at which point the spray tube 24 will be reversed and accelerated from 0 r.p.m. to 600 r.p.m. It is within the purview of this invention to design the bimetallic strip vanes 176 and 178to produce any desired maximum rotating speed for the spray tube 24 and to select the desired temperature rise necessary to actuate the vanes from one extreme to the other.

It should now be seen that means have been provided in a washing appliance fluid distribution system for altering the method of distribution in accordance with a changing condition within the appliance. This is effective to change continuously the manner in which washing fluid is sprayed over the items to be washed and to increase the washing efiiciency of the appliance.

While the forms of embodiment of the invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.

What is claimed is as follows:

1. A dishwashing appliance having a washing chamber and utensil containers in said chamber comprising, means for admitting water to said chamber, means for collecting said water in one portion of said chamber, means for distributing water in said chamber, conduit means connecting said collecting portion and said distributing means, means for circulating water from said collecting portion through said conduit means to saiddistributing means, said conduit means having means for imparting a swirl to said circulating water to rotate said distributing means in one direction, and means for moving said swirl imparting means for changing the rotation of said distributing means.

2. A dishwashing appliance having a washing chamber and utensil containers in said chamber comprising, means for admitting water to said chamber, means for collecting said water in one portion of said chamber, means for distributing water in said chamber, conduit means connecting said collecting portion and said distributing means, means for circulating water from said collecting portion through said conduit means to said distributing means, said conduit means having means for imparting a rotary motion to said circulating water to rotate said distributing means in one direction at one speed, and means for moving said rotary motion imparting means for rotating said distributing means in another direction at another speed.

3. The dishwashing appliance of claim 2 wherein said moving means is thermally responsive to a condition in said chamber.

4. An appliance having a fluid distribution chamber comprising, a reversely movable fluid distribution means in said chamber, a fluid impelling means connected to said distribution means, variable flow directional means for causing said fluid to rotate when in said fluid distribution means for selectively motivating said fluid distribution means in a plurality of directions, and means for controlling said flow directional means.

5. The appliance of claim 4 wherein said controlling means is thermally responsive,

6. The appliance of claim 4 wherein said controlling means is actuated in timed sequence.

7. The appliance of claim 4 wherein said controlling means is responsive to a changing condition in said chamber.

8. A dishwasher having a dishwashing chamber comprising, a sump in the bottom of said chamber, a swirl actuated rotatably mounted spray tube in said chamber, a pump connected to said sump, a conduit leading from said pump to said spray tube, said conduit having a header adjacent one end of said spray tube, said header including a first swirl imparting vane having an upper position and a second swirl imparting vane having a lower position, and means for changing the position of said vanes, thereby to alter the rotation of said spray tube.

9. An appliance having a chamber comprising, a sump for collecting heated water, a swirl actuated rotatably mounted spray tube, a pump connected to said sump, a conduit leading from said pump to said spray tube, said conduit having a header adjacent one end of said spray tube, said header including a first bimetallic swirl imparting vane having a normal first position and a second bimetallic swirl imparting vane having a normal second position, and means for energizing said pump to force said water over said vanes to said spray tube, whereby the temperature of said water alters the positions of said; swirl imparting vanes. i

10. A dishwasher having a dishwashing chamber com-' prising, a swirl actuated rotatably mounted spray tube, a pump connected to said chamber, means connecting said pump to said spray tube, said connecting means including a header, said header including a first swirl imparting vane having a first position and a second swirl imparting vane having a second position, and means for changing the position of said vanes, thereby to alter the rotation of said spray tube.

11. A cleansing appliance having a washing chamber and utensil containers in said chamber comprising, means for admitting water to said chamber, means for collecting said water in one portion of said chamber, means for distributing water in said chamber, conduit means connect ing said collecting portion and said distributing means, means for circulating water from said colleting portion through said conduit means to said distributing means,

said conduit means having means for imparting a swirl to said circulating water to rotate said distributing means in two directions, and means for continously oscillatingly moving said swirl imparting means for changing the rotation of said distributing means, said moving means in cluding a thermally responsive bimetallic spiral element.

12. A cleansing appliance having a washing chamber and utensil containers in said chamber comprising, means for admitting water to said chamber, means for collecting said water in one portion of said chamber, means for distributing water in said chamber, conduit means connecting said collecting portion and said distributing means and means for circulating water from said collecting portion through said conduit means to said distributing means, said conduit means having means in the path of said circulating water for imparting a swirl to said circulating water to rotate said distributing means, and said swirl imparting means including a pair of oppositely functioning thermally responsive bimetallic strips movably rcsponsive to the temperature of said water to alter said swirl.

13. A cleansing appliance having a washing chamber and utensil containers in said chamber comprising means for admitting water to said chamber, means for collecting said water in one portion of said chamber, means for distributing water in said chamber, conduit means con necting said collecting portion and said distributing means, means for circulating water from said collecting portion through said conduit means to said distributing means, said conduit means having means for'imparting a swirl to said circulating water to rotate said distributing means, means for moving said swirl imparting means for changing the swirl imparted to said water, and adjustable timer actuated means for controlling the extent to which said moving means changes the swirl imparted to said water.

14. An appliance having a cleansing chamber, spray means in said chamber and means for directing a cleansing fluid to said spray means comprising, an inlet housing rotatably supporting one end of said spray means, a vane in said housing for imparting a swirl to said cleansing fluid, a shaft for pivotally carrying said vane, and a spiral temperature responsive element coaxial with said shaft and having one portion aflixed to said shaft and another portion aflixed to said housing, whereby said vane is alternatingly shifted with change of temperature in said chamber.

2,678,050 2,808,063 Abresch et al Oct. 1, 1957 2,844,408

Dickmann et al. July 22, 1958 

